Nickel modified catalyst for the production of hydroxy ether hydrocarbons by vapor phase hydrogenolysis of cyclic acetals and ketals

ABSTRACT

Catalyst compositions of alumina supports containing palladium and nickel are selective in a vapor phase hydrogenolysis reaction to convert cyclic acetal compounds and/or cyclic ketal compounds in the presence of hydrogen to their corresponding hydroxy ether hydrocarbon reaction products.

1. CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/168,361 filed on Jun. 24, 2011.

2. FIELD OF THE INVENTION

The invention relates to a catalyst composition and to the production ofhydroxy ether hydrocarbons from the hydrogenolysis of cyclic acetals orcyclic ketals in the vapor phase using the catalyst composition.

3. BACKGROUND OF THE INVENTION

Acetals and ketals are readily obtained by the reaction of aldehyde orketone hydrocarbons and polyhydroxy hydrocarbons by many methods wellknown in the art. There are many references to the efficient preparationof these materials. It is desirable to prepare 2-alkoxy-ethanolcompounds, such as 2-n-butoxyethanol and 2-n-propoxyethanol without therequirement of using ethylene oxide as the reactant. It is alsodesirable to have a process which is robust enough to prepare otherhydroxy ether compounds without the requirement of using other highlyreactive epoxy compounds and similar materials such as propylene oxide,1,2-epoxybutane, glycidol (2,3-epoxy-1-propanol) and trimethylene oxide.It is also desirable to prepare hydroxy ether compounds in highselectivity without requiring alkylating agents such as alkyl bromides,chlorides and sulfates in their reaction with polyhydroxy compounds in aWilliamson ether synthesis with the concurrent production of wastesalts.

The classes of compounds known as hydroxy ether hydrocarbons have greatvalue as solvents and dispersants for latex paints and other coatings.They also have value as components of industrial and consumer cleaningsolutions and surfactants and raw materials for the preparation ofpolyurethane materials. The large bulk of this class of compounds thatare commercially available are generally known as “E-series” and“P-series” solvents. The “E-series” solvents are prepared by thereaction of ethylene oxide (EO) with corresponding alcohols to form the“E-series” products. Conversely, the “P-series” of solvents are preparedby the reaction of propylene oxide (PO) with corresponding alcohols toform similar materials. This technology has a number of concerns anddifficulties. First, ethylene oxide and propylene oxide are hazardousmaterials. Likewise, the nature of the reaction of an alcohol withhighly reactive epoxides generates relatively low selectivity fordesirable mono addition of EO or PO to the alcohol resulting in di-, triand poly-EO or PO addition products in significant amounts. Third, thetechnology of mono ethylene glycol (MEG) production is moving away fromthe traditional isolation of ethylene oxide and subsequent reaction withwater toward more efficient methods to prepare MEG in higher yield thatuse other technology, such as ethylene carbonate and direct waterquenching of crude EO reactor product. These newer technologies remove aready source of on-site EO for the production of E-series products.Fourthly, historically, a large capital intensive EO/MEG facility needsto be located in close proximity to the alcohol production facility tobe efficient and avoid the risk of having to transport EO over longdistances. In the case of “P-series” products, a propylene oxide unitalso has to be conveniently located. The traditional preparation of POinvolves the co-product formation of precursor materials leading tofinal products such as styrene and MTBE. Other methods to make PO havebeen developed, as for example, by the use of expensive hydrogenperoxide. The use of PO to make P-series materials thus has costconcerns.

Dioxolane compounds are characterized by having a five-membered ringwith oxygen atoms in the 1 and 3 positions. Other materials based onrenewable materials can also be used to prepare acetal compounds byknown reactions with aldehydes, including glycerin, 1,3-propanediol andsugar-derived polyols such as mannitol, erythritol, 1,2- and2,3-butanediol, and the like. In some of these other examples a class ofacetal compound having a six-membered ring with oxygen atoms in the 1and 3 positions known as 1,3-dioxanes can be prepared. Ketals may alsobe prepared by the reaction of ketone hydrocarbons with the above polyhydroxyl hydrocarbons in a similar manner to that of the preparation ofacetals.

Previous work has been disclosed in the literature that discusses thehydrogenolysis of acetals, both cyclic and open to produce ether typehydrocarbons. In the case of 1,3-dioxolane acetal compounds, work hasbeen disclosed that describes the preparation of valuable 2-alkoxyethanol compounds. This chemical transformation is carried out by thecleavage of the oxygen-carbon bond attached to the carbon in the2-position of the ring with hydrogen using a noble metal catalyst. Thefocus of that work has been on the liquid-phase hydrogenolysis ofacetals in a solvent that is typically the diol moiety used to preparethe cyclic acetal. The art teaches the importance of having a largeexcess of this diol solvent present during the hydrogenolysis reactionto prevent the formation of significant amounts of undesired co-product,namely a diether.

U.S. Pat. No. 4,479,017 discusses the desire to generate ether compoundsin high selectivity and yield by employing a palladium catalyst on acarbon carrier support in the absence of an added acid promotercompound. U.S. Pat. No. 4,484,009 discloses the product of monoethers ofmonoethylene glycol by hydrogenolysis of an acetal with a co-catalyticsystem of a palladium catalyst in combination with an acidic phosphoruspromoter compound and ethylene glycol. In both instances, the reactionswere conducted in the liquid phase. There remains a need to providesuitable catalyst systems that will generate hydroxy ether hydrocarbonsin high selectivity in a vapor phase hydrogenolysis process.

4. SUMMARY OF THE INVENTION

There is now provided a process comprising contacting hydrogen with acyclic compound comprising a cyclic acetal or a cyclic ketal in thevapor phase in the presence of a catalyst composition to produce ahydroxy ether hydrocarbon, wherein the catalyst composition comprises analuminum oxide support containing or on which is deposited:

-   -   i. palladium present in an amount of at least 0.8 wt % and up to        5 wt % based on the weight of the catalyst composition, and    -   ii. nickel present in an amount of 500 ppmw up to 3000 ppmw.

There is also provided a process of:

-   -   (a) feeding hydrogen and the cyclic compound composition to a        reaction zone within a reaction vessel, and    -   (b) conducting a reaction in the reaction zone comprising        contacting hydrogen with at least a portion of the cyclic        compound composition in the presence a catalyst composition in        the reaction zone under reaction zone conditions above the dew        point of the cyclic compound composition to produce hydroxy        ether hydrocarbons, fed to the reaction zone, and    -   (c) withdrawing a product stream from the reaction zone        comprising hydroxy ether hydrocarbons, hydrogen, and if present        any unreacted cyclic compounds;        wherein the catalyst composition comprises an aluminum oxide        support containing or on which is deposited:    -   i. palladium present in an amount of at least 0.8 wt % and up to        5 wt % based on the weight of the catalyst composition, and    -   ii. nickel present in an amount of 500 ppmw up to 3000 ppmw        based on the weight of the catalyst composition.

There is also now provided a process comprising contacting cycliccompounds in the vapor phase with hydrogen in the presence of thiscatalyst composition and in a reaction zone to produce a vapor hydroxyether hydrocarbon, wherein said cyclic compounds comprise cyclicacetals, cyclic ketals, or a combination thereof.

5. DETAILED DESCRIPTION OF THE INVENTION

As used herein, “cyclic compounds” includes cyclic acetal compounds,cyclic ketal compounds, and combinations thereof. The term “within”includes the end points of a range.

We have surprisingly found that an efficient hydrogenolysis reaction canbe carried out to transform cyclic compounds, such as 1,3-dioxolanecompounds and 1,3-dioxane classes of compounds, with high selectivity ina vapor phase reaction using catalysts having a combination of features.Improving the selectivity to the production of the desired hydroxy ethermono-hydrocarbon is the criteria of choice because the unconvertedcompounds can be recycled for conversion to the desired hydroxy etherhydrocarbon, whereas catalysts with high activity but low selectivityare problematic because the cyclic acetals can be converted toby-products which have no possibility of further conversion to desiredhydroxy ether mono-hydrocarbons.

We have found that a particular catalyst is highly selective forobtaining the desired hydroxyl ether hydrocarbon product, often ingreater than 90% molar selectivity from the converted acetal feedmaterial. The catalyst compositions used in the process of the inventionis an aluminum oxide support containing or on which is deposited:

-   -   i. palladium present in an amount of at least 0.8 wt % and up to        5 wt % based on the weight of the catalyst composition, and    -   ii. nickel present in an amount of 100 ppmw up to 5000 ppmw.

Aluminum oxide has many phases. Suitable phases include alpha, gamma,theta, and delta. For some catalyst compositions of the invention, thephases include the alpha and gamma phases. Each of these phases andtheir characterization are well known. For example, the α-alumina(alpha) phase has a hexagonal crystal structure which is the mostthermodynamically stable form. γ-alumina (gamma) typically has a cubiccrystal structure which is also stable at the operating temperatures ofthe invention. θ-alumina (theta) crystal structure can be characterizedas typically having a monoclinic crystal structure, although the crystalstructure can vary depending on the calcining temperature. The crystalstructure of these forms are known and described in, for example, KirkOthmer Encyclopedia of Chemical Technology, Volume 2, pages 302-317(1992).

An α-aluminum oxide support desirably contains more than 95% of itscrystal phases in the alpha phase. These ultrapure alpha phase aluminumoxide supports are desirable. Such high purity supports contain at least97%, or at least 98%, or at least 99% of their phases in the alphaphase. α-aluminum oxide supports that have less than 90% alpha phasecontent often also contain high amounts of silicon oxide. Aluminasupports with high contents of silicon oxide impact the selectivity ofthe catalyst toward the production of the desired hydroxy ethermono-hydrocarbon. γ-alumina supports have a gamma phase content of atleast 95%, or at least 96%, or at least 97%, or at least 98%, or atleast 99%. θ-alumina supports have a theta phase content of at least95%, or at least 96%, or at least 97%, or at least 98%, or at least 99%.Like the alpha phase aluminum oxide supports, silicon oxides such assilicon dioxide poison the selectivity of the catalyst toward theproduction of hydroxy ether mono-hydrocarbon compounds.

The BET surface area (determined by the BET method by nitrogenadsorption to DIN 9277) of the aluminum oxide support is at least 0.1m2/g, or at least 0.2 m2/g, or at least 0.5 m2/g. or at least 1 m2/g. orat least 2 m2/g. or at least 3 m2/g and up to 350 m2/g, or less than 300m2/g, and at least 100 m2/g, or at least 150 m2/g, or at least 200 m2/g.

Aluminum oxide supports with a low weight percentage of palladiumloading generally yield catalysts that reduce the formation ofbyproducts such as diether compounds, ester compounds and otherby-products that result from unselective reactions upon the cycliccompound feed and by secondary decomposition of liberated ethyleneglycol, a co-product of diether formation. Surprisingly, the catalystcomposition of the invention having high palladium loadings were highlyselective to the production of the desired hydroxy ether hydrocarbons.The catalyst composition used in this invention has a high loading ofpalladium. Suitable palladium metal catalyst loadings for the catalystused in the invention are at least 0.8 wt %, or at least 0.9 wt %, or atleast 1.0 wt %, or more than 1.0 wt %, or at least 1.05 wt %, or atleast 1.1 wt %, or at least 1.2 wt %, or at least 1.3 wt %, or at least1.4 wt %, or at least 1.5 wt %, and up to or less than 5.0 wt %, or upto 3.0 wt %, or up to 2.0 wt %, or up to 1.5 wt %

Palladium can be loaded onto the supports by any conventional means.Palladium can be added as a metal or as a compound, such as palladiumchloride, palladium chloride dihydrate, palladium bromide, palladiumiodide, palladium oxide, or an organic palladium salt or complex such aspalladium formate, palladium acetate, palladium butyrate and palladiumacetylacetonate.

The catalyst compositions of the invention desirably have a low silicondioxide content to improve the selectivity and yield to the product ofhydroxy ether mono-hydrocarbon compounds. The supports for the catalystsmay have a SiO₂ content of no more than 1.0 wt %, or less than 0.5 wt %,or less than 0.3 wt %, or no more than 0.2 wt %, or no more than 0.1 wt%. Those with low contents of silicon dioxide are effective atincreasing selectivity.

The catalyst composition used in the process of the invention is dopedwith nickel. The use of nickel in certain amounts in combination withhigh loadings of palladium will increase the selectivity of convertedacetal into desired products, even though high loadings of palladium arethought to be highly active but poorly selective. Nickel deposited ontothe catalyst support may have an oxidation state of zero or other thanzero. Suitable salts of nickel include organic anions, such as C1-C8carboxylates and halides such as acetate, chloride and fluoride,bromides, nitrates, carbonates, sulphates, sulfides, hydroxides,ammonium nickel salts, and the like. Specific examples of such modifiersused to dope the supports include ammonium nickel(II) sulfate,bis(ethylenediamine)nickel(II) chloride, hexaamminenickel(II) iodide,nickel carbonate, nickel(II) acetate, nickel(II) bromide 2-methoxyethylether, nickel(II) bromide, nickel(II) bromide ethylene glycol dimethylether complex, nickel(II) carbonate hydroxide, nickel(II) chloride,nickel(II) cyclohexanebutyrate, nickel(II) fluoride, nickel(II)hydroxide, nickel(II) iodide, nickel(II) molybdate, nickel(II) nitrate,nickel(II) oxalate, nickel(II) perchlorate, nickel(II) sulfamate,nickel(II) sulfate, potassium nickel(IV) paraperiodate, potassiumtetracyanonickelate(II) potassium tetracyanonickelate(II) hydrate,nickel (II) oxide, bis(cyclcooctadiene)nickel, and nickel tetracarbonyl,and the like.

The amount of nickel on the alumina support is sufficient to obtainimproved selectivity over the same catalyst without nickel whileobtaining an acceptable drop in activity. A drop in activity isacceptable because with high selectivity, unconverted compounds can berecycled for additional passes to obtain the desired hydroxy eithermonohydrocarbon compounds.

Suitable amounts of nickel are at least 100 ppmw, or at least 250 ppmw,or at least 500 ppmw, or at least 700 ppmw, or at least 900 ppmw, or atleast 1000 ppmw, and up to 5000 ppmw, or up to 4000 ppmw, or up to 3000ppmw, or up to 2500 ppmw, or up to 2000 ppmw, or up to 1750 ppmw, or upto 1500 ppmw, or up to 1250 ppmw.

Additional examples are amounts in a range of 100-5000, or 100-4000, or100-3000, or 250-3000, or 250-2500, or 250-2000, or 250-1500, or250-1250, or 500-3000, or 500-2500, or 500-2000, or 500-1500, or500-1250, each in ppmw, based on the weight of the catalyst composition.

With some palladium catalysts on alumina supports, the addition ofalkali or alkaline earth metal dopants have enhanced the selectivity ofthe catalyst toward the production of hydroxy ether mono-hydrocarbons.The addition of alkali metals to this palladium catalyst on alumina doesnot appear to enhance selectivity and in some circumstances, decreasesselectivity. In addition, the activity of the catalyst is depressed to alevel below that of industrial relevance. Thus, in a preferred aspect ofthe invention, the catalyst composition is free of alkali metalcompounds present in significant quantities, that is, in amountexceeding 50 ppm, or in amounts exceeding 40 ppmw, or in amountsexceeding 30 ppmw, or in amounts exceeding 20 ppmw, or in amountsexceeding 10 ppmw, or in amounts exceeding 5 ppmw. In anotherembodiment, the catalyst composition is also free of alkaline earthmetals in the same quantities.

The catalyst composition used in the process of the invention provide aselectivity to the production of hydroxy ether mono-hydrocarbons to alevel of at least 80%, or at least 82%, or at least 84%, or at least86%, or at least 88%, or at least 90%, or at least 92%, or at least 94%,or at least 95%. The conversion rates from the cyclic compounds to anyand all converted reaction products is desirably at least 65%, or atleast 70%, or at least 75%, or at least 80%, or at least 90%, or atleast 92%, or at least 94%, or at least 95%. By avoiding a large drop inconversion, the production rate remains acceptable.

The hydroxy ether mono-hydrocarbons have both (i) at least one etherlinkage and (ii) at least one hydroxyl group, and in addition, are thosecompounds in which the reaction product of cyclic acetal or cyclic ketalwith one or more moles of hydrogen has not reacted any further withother cyclic acetals or cyclic ketals or other reaction products ofcyclic acetals and cyclic ketals and hydrogen, and has not beensubjected to a decrease in its molecular weight due to chain scission.If the cyclic acetal or ketal compound fed to the reaction zone contains2 or more ether linkages to start, but does not react with any othercyclic acetal or cyclic ketal compounds or any other reaction productsof hydrogen with cyclic acetals or cyclic ketals, it is deemed a hydroxyether mono-hydrocarbon even though more than one ether linkage ispresent. This is because the reaction product of hydrogen and the cyclicacetal or cyclic ketal having multiple ether linkages has not reactedany further with other cyclic acetals or with any other reactionproducts of hydrogen and cyclic acetals or cyclic ketals.

The catalysts of the invention also are effective to suppress theformation of diether by-product compounds. It is advantageous to use acatalyst composition that, even though a significant improvement inselectivity is not observed, nevertheless results in the formation offewer diether by-products. A product stream composition from a vaporphase hydrogenolysis of cyclic hydrocarbons that contains up to 5 wt %of diether compound co-products, or up to 4 wt %, or up to 3 wt %, or upto 2 wt %, or up to 1 wt % are also suitable.

The aluminum oxide supports may be obtained from natural sources orsynthesized, such as by calcination of aluminum hydroxide.

The shape of the solid catalysts are not particularly limited but shouldbe of a shape and size and robust enough to resist breaking in acatalyst bed. Spherical, star, and trilobal shapes are suitable for usein the invention.

The average particle sizes of the catalysts are not particularlylimited. Shapes can be selected to provide efficient mass transfer.Suitable average particle sizes range from 0.1 mm to 8 mm, with 1 mm to6 mm well suited in the practice of the invention.

The average pore size and pore volume of the supports is notparticularly limited. Consideration is given for having pore sizes andpore density to support the palladium metal and provide active sites forthe conversion of cyclic compounds to the hydroxy ether mono-hydrocarboncompounds. Typical average pore sizes range from 30 Å to 300 Å, or 60 Åto 200 Å, and typical pore volumes range from 0.2 cc/g to 1.0 cc/g, or0.3 cc/g to 0.8 cc/g.

In the process of the invention, cyclic compounds in a cyclic compoundcomposition are contacted with hydrogen in the vapor phase to producehydroxy ether hydrocarbons. The cyclic compounds are in the vapor phaseat least in the reaction zone and desirably also fed to the reactionzone in the vapor phase. For example, one may hydrogenate the cycliccompounds by:

-   -   (a) feeding hydrogen and a cyclic compound composition        comprising cyclic compounds, and preferably a cyclic compound        vapor composition, to a reaction zone within a reaction vessel,        and    -   (b) contacting at least a portion of the cyclic compound        composition with hydrogen in the reaction zone under reaction        zone conditions above the dew point of the cyclic compound        composition fed to the reaction zone to produce hydroxy ether        compounds in the reaction zone, and    -   (c) withdrawing a product stream from the reaction zone        comprising hydroxy ether hydrocarbons, hydrogen, and if present        any unreacted cyclic compounds.

The cyclic compounds can be contacted with hydrogen in a reaction zoneover a noble metal catalyst advantageously in the absence of a liquid,such as a solvent like ethylene glycol, in the reaction zone during thehydrogenolysis reaction. Also, advantageously, the noble metal catalystdoes not need to be separated from the product stream effluent becausethe reaction proceeds in the vapor phase over a heterogeneous catalystbed, preferably a fixed bed.

The cyclic compound composition of the invention contains cycliccompounds. The cyclic compounds that are contacted with hydrogen in theprocess of the invention are those having a cyclic acetal or ketalmoiety. The cyclic acetal moiety produced in the process of theinvention has two oxygen atoms single bonded to the same carbon atom inthe ring structure. Examples include cyclic compounds having1,3-dioxolane moieties and dioxane moieties (especially 1,3-dioxanemoieties), as well as those having larger rings with oxygen atoms in the1,3 position.

In one embodiment, the cyclic compound(s) may be represented by thegeneral formula:

wherein R¹, R², R³, and R⁴ are independently H; an branched orun-branched C₁-C₅₀ alkyl, C₂-C₅₀ alkenyl, aryl-C₁-C₅₀ alkyl, aryl-C₂-C₅₀alkenyl-, C₃-C₁₂ cylcoalkyl, or a C₃-C₅₀ carboxylate ester; and whereinthe alkyl, alkenyl, aryl, and cycloalkyl groups of R¹, R², R³, and R⁴are optionally substituted with 1, 2, or 3 groups independently selectedfrom —OH, halogen, dialkylamino, aldehyde, ketone, carboxylic acid,ester, ether, alkynyl, dialkylamide, anhydride, carbonate, epoxide,lactone, lactam, phosphine, silyl, thioether, thiol, and phenol;

and any one or both of R³ and R⁴ are optionally independently ahydroxyl, halogen, dialkylamino, amine, aldehyde, ketone, carboxylicacid, ester, ether, alkynyl, dialkylamide, anhydride, carbonate,epoxide, lactone, lactam, phosphine, silyl, thioether, thiol, or phenol;

and wherein R¹ and R² are not both H;

and R¹ and R² optionally together form a cycloalkyl having 3-12 carbonatoms;

and wherein R⁵ is branched or unbranched, substituted or unsubstituted,divalent alkyl or divalent alkenyl group each having 1 to 8 carbon atomsand optionally containing 1, 2, or 3 oxygen atoms in the alkyl oralkenyl group;

and wherein n is an integer selected from 0 or 1.

R¹, R², R³, and R⁴ may independently be H, or a branched or un-branchedC₁-C₆ alkyl group. Or, R¹, R², R³, and R⁴ may independently be H, or abranched or un-branched C₁-C₄ alkyl group. R¹ may be a branched orunbranched C₁-C₆ alkyl group while R² is a hydrogen atom.

R⁵ may be a branched or unbranched divalent alkyl group having 1 to 6,or 1 to 4, or 1 to 3, or 1 to 2 carbon atoms.

Examples of cyclic acetals include 2-propyl-1,3-dioxolane,2-propyl-1,3-dioxane, 2-ethyl-1,3-dioxolane, 2-ethyl-1,3-dioxane,2-methyl-1,3-dioxolane, 2-methyl-1,3-dixoane,2-propyl-4-methyl-1,3-dioxane, 5,5-dimethyl-2-propyl-1,3-dioxane,5,5-dimethyl-2-ethyl-1,3-dioxane,4-hydroxymethyl-2-propyl-1,3-dioxolane,4-hydroxymethyl-2-propyl-1,3-dioxane, 2-ethyl-1,3-dioxepane,2-ethyl-1,3,6-trioxocane.

As to substituents, in one embodiment, R³ or R⁴ is a hydroxyl group.

In the case one desires to use a cyclic acetal compound as a startingmaterial, one of R¹ or R² is a hydrogen atom. R¹ and R² mayindependently be H, or a branched or un-branched C₁-C₆ alkyl group. Or,R¹ and R² may independently be H, or a branched or un-branched C₁-C₄alkyl group. R¹ may be a branched or unbranched C₁-C₆ alkyl group whileR² is a hydrogen atom. Particularly useful cyclic acetals for thisinvention leading to useful materials of commerce include 1,3-dioxolaneshaving R¹ being an alkyl group that can lead to “E-series” typesolvents. Likewise, 1,3-dioxolanes having R¹ being an alkyl group and R³being a methyl group can lead to “P-series” type solvents.

In the case one desires to start with a cyclic ketal compound as thestarting material, then neither R¹ nor R² are hydrogen atoms. R¹ and R²may independently be a branched or un-branched C₁-C₆ alkyl group. Or, R¹and R² may independently be a branched or un-branched C₁-C₄ alkyl group.Other potentially useful acetals that make use of 1,3-propylene glycoland glycerin in their preparation would include 1,3-dioxane acetalshaving R¹ being an alkyl group and 1,3-dioxane acetals having R¹ beingan alkyl group and R⁴ being a hydroxyl group. A variation of theglycerin acetals that have potentially useful derivatives would be1,3-dioxolane acetals having R¹ being an alkyl group and R³ being ahydroxymethyl group.

Examples of cyclic acetals that have 1,3-dioxolane moieties include2-propyl-1,3-dioxolane, 2-propyl-1,3-dioxolane, 2-ethyl-1,3-dioxolane,2-methyl-1,3-dioxolane, 4-hydroxymethyl-2-propyl-1,3-dioxolane.

Examples of cyclic acetals that have 1,3-dioxane moieties include2-propyl-1,3-dioxane, 2-ethyl-1,3-dioxane, 2-methyl-1,3-dixoane,2-propyl-4-methyl-1,3-dioxane, 5,5-dimethyl-2-propyl-1,3-dioxane,5,5-dimethyl-2-ethyl-1,3-dioxane, and4-hydroxymethyl-2-propyl-1,3-dioxane.

Examples of cyclic ketals that can be utilized in the present inventioninclude, but are not limited to, 2,2-dimethyl-1,3-dioxolane,2,2-dimethyl-1,3-dioxane, 2,2,4-trimethyl-1,3-dioxolane,2,2-dimethyl-1,3-dioxepane, 2,2-dimethyl-1,3,6-trioxocane,4-methanol-2,2-dimethyl-1,3-dioxolane, 2,2-dimethyl-1,3-dioxan-5-ol,2,2,5,5-tetramethyl-1,3-dioxane, 2-ethyl-2-methyl-1,3-dioxolane,2-ethyl-2-methyl-1,3-dioxane, 2-ethyl-2,4-dimethyl-1,3-dioxane,2-ethyl-2-methyl-1,3-dioxepane, 2-ethyl-2-methyl-1,3,6-trioxocane,2-ethyl-2,5,5-trimethyl-1,3-dioxane,4-methanol-2-ethyl-2-methyl-1,3-dioxolane,2-ethyl-2-methyl-1,3-dioxan-5-ol, 2-methyl-2-propyl-1,3-dioxolane,2-methyl-2-propyl-1,3-dioxane, 2,4-dimethyl-2-propyl-1,3-dioxane,2-methyl-2-propyl-1,3-dioxepane, 2-methyl-2-propyl-1,3,6-trioxocane,2,5,5-trimethyl-2-propyl-1,3-dioxane,4-methanol-2-methyl-2-propyl-1,3-dioxolane,2-methyl-2-propyl-1,3-dioxan-5-ol, 2-methyl-2-pentyl-1,3-dioxolane,2-methyl-2-pentyl-1,3-dioxane, 2,4-dimethyl-2-pentyl-1,3-dioxane,2-methyl-2-pentyl-1,3-dioxepane, 2-methyl-2-pentyl-1,3,6-trioxocane,2,5,5-trimethyl-2-pentyl-1,3-dioxane,4-methanol-2-methyl-2-pentyl-1,3-dioxolane, and2-methyl-2-pentyl-1,3-dioxan-5-ol.

The cyclic acetals and ketals are prepared by reacting a polyhydroxylcompound with a carbonyl functional compound that is either an aldehydeor a ketone, in the present of an acid catalyst.

The cyclic acetals and ketals are prepared by reacting a polyhydroxylcompound with a carbonyl functional compound that is either an aldehydeor a ketone, in the present of an acid catalyst.

The polyhydroxyl compounds have at least two hydroxyl (—OH)functionalities. The polyhydroxyl compounds may contain ether or esterlinkages in the longest carbon chain.

Suitable polyhydroxyl compounds for the present invention include, butare not limited to ethylene glycol, 1,2-propanediol, 1,3-propanediol,1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 1,2-pentanediol,2,4-pentandiol, 2,2-dimethyl-1,3-propanediol, diethyleneglycol, andtriethyleneglycol, glycerin, trimethylolpropane, xylitol, arabitol, 1,2-or 1,3cyclopentanediol, 1,2- or 1,3-cyclohexanediol, and2,3-norbornanediol.

The carbonyl compounds contain at least one carbonyl functionality. Inthe present invention, any carbonyl compound may be used.

For example, the carbonyl compound is represented by the formula:

R¹R²C═O

in which R¹ and R² are independently H, C₁-C₅₀ alkyl, C₂-C₅₀ alkenyl,aryl-C₁-C₅₀ alkyl, aryl-C₂-C₅₀ alkenyl-, or C₃-C₁₂ cylcoalkyl, andwherein the alkyl, alkenyl, aryl, and cycloalkyl groups of R¹ areoptionally saturated or unsaturated, and branched or unbranched orsubstituted or unsubstituted with 1, 2, or 3 groups comprising —OH,halogen, dialkylamino, C₁-C₆ alkyl, aldehyde, ketone, carboxylic acid,ester, ether, alkynyl, dialkylamide, anhydride, carbonate, epoxide,lactone, lactam, phosphine, silyl, thioether, thiol, aryl, phenol, orcombinations thereof. R¹ and R² optionally together form a cycloalkylhaving 3-12 carbon atoms;

When one of R¹ and R² is hydrogen, the carbonyl compound is an aldehydecompound. The aldehyde compound may have, if desired, at least onealdehyde functional group wherein the aldehyde carbon atom is bonded toa (i) branched or unbranched C₁-C₉ alkyl group or (ii) an aryl oralicyclic group which is optionally substituted with a branched orunbranched C₁-C₉ alkyl group.

Examples of an aldehyde compounds include, but are not limited to,formaldehyde, benzaldehyde, acetaldehyde, propionaldehyde,butyraldehyde, isobutyraldehyde, pentaldehyde, 2-methylbutyraldehyde,3-methylbutyraldehyde, n-pentanal, isopentanal, hexaldehyde,heptaldehyde, 2-ethylhexaldehyde, octanal, nonanal, n-decanal,2-methylundecanal, lauryl aldehyde, myristyl aldehyde, cetyl aldehyde,stearyl aldehyde, behenyl aldehyde, glutaraldehyde, acrolein,crotonaldehyde, oleyl aldehyde, linoleyl aldehyde, linolenyl aldehyde,erucyl aldehyde, cinnamaldehyde, 1,3-cyclohexanedicarboxaldehyde,1,4-cyclohexanedicarboxaldehyde, and combinations thereof.

Preferably, the aldehyde compound is 2-ethylhexaldehyde or an aliphaticaldehyde compound wherein the aldehyde carbon atom is bonded to abranched or unbranched C₁-C₅ alkyl group (for a total of 2-6 carbonatoms). Examples of the latter compounds include acetaldehyde,propionaldehyde, butyraldehyde, isobutyraldehyde, pentaldehyde,2-methylbutyraldehyde, 3-methylbutyraldehyde, hexaldehyde, benzaldehyde,2-ethylhexaldehyde, octanal, nonanal.

When neither R¹ nor R² is hydrogen, the carbonyl compound is a ketone.Examples of suitable ketone compounds include, but are not limited to,acetone, methyl isobutyl ketone (2-butanone), methyl ethyl ketone,methyl propyl ketone (2-pentanone), methyl isopropyl ketone(3-methyl-2-butanone), methyl isobutyl ketone (4-methyl-2-pentanone),2-hexanone, cyclohexanone, 2-heptanone (methyl amyl ketone),4-heptanone, and 2-octonone.

The starting feed materials used in the process of the inventioncomprise cyclic acetal compounds or cyclic ketal compound orcombinations thereof. The process of the invention is a vapor phasereaction conducted at an elevated pressure. Therefore, the feedmaterials selected should be sufficiently volatile to enter the reactionvessel in a gaseous state as a gaseous feed stream. Accordingly, thefeed materials must have a pure liquid vapor pressure of at least 1 mmHg (0.133 kPa) (at the reaction temperature). To obtain better reactionrates, it is desired to select a feed material that has a vapor pressurein excess of 10 mm Hg (1.33 kPa).

For example, feed material compounds with relatively high boiling pointslike a cyclic acetal or ketal compound can be selected with high boilingpoints (at 1 atm) in excess of 200° C. or even at least 250° C. (523degrees K) because those same compounds may have practical vaporpressures of in excess of 50 mm Hg or at least 70 mm Hg (9.33 kPa) attypical hydrogenolysis reaction temperatures (at least 150° C., or atleast 180° C. or at least 190° C. or at least 200° C.) in the reactionvessel.

The process has the ability to be operated at a wide range of reactiontemperature conditions. Suitable reaction temperatures (reactor setpoints) range from at least 100° C., or at least 130° C., or at least150° C., or at least 170° C., or at least 180° C., or at least 190° C.,or at least 200° C., or at least 210° C., or at least 220° C., and up to300° C., or up to 275° C., or up to 250° C., or up to 240° C., or up to230° C., or up to 220° C., or up to 210° C., or up to 200° C.

The favored temperature range for the practice of the invention is atleast 150° C. because reaction rates increase at higher temperatures andup to about 250° C. Temperatures in excess of 250° C. start to sufferfrom excessive side product reactions. Suitable ranges include 190° to250° C., or 200° to 230° C.

The efficiency of the process is increased if the operating reactionconditions are at temperatures above the dew point of the cycliccompound composition in the gaseous feed stream at reaction pressure. Inanother embodiment, the operating reaction conditions are at atemperature above the dew point of both the cyclic compound compositionand the reaction products of the cyclic acetals in the gaseous productstream.

Dew point is defined as the temperature and pressure at which liquidcondensation begins to take place for a gaseous mixture having acondensable material. See Dictionary of Scientific and Technical Termspublished by McGraw-Hill, Fifth Edition, 1994. In practice, dew point iscontrolled by a combination of factors. The first factor is the actualvapor pressure of a pure liquid as a function of temperature. Increasingtemperature increases the vapor pressure of a pure liquid thereby makingit less likely to condense at higher temperature. Cyclic acetals andketals behave in this manner. Lowering the temperature also lowers thevapor pressure of the liquid. Thus, operating the reaction at lowertemperatures will require lowering the pressure in the reaction vesselto prevent the cyclic acetals from dropping below their dew point. It isdesirable to conduct the hydrogenolysis at elevated temperatures inorder to keep materials from condensing into a liquid phase at reactionconditions.

The second factor that keeps the cyclic compounds in the gaseous stateand prevents them from dropping below their dew points is to keep thereactor absolute pressure low enough to keep the actual partial pressureof the component cyclic acetals above the dew point in the gaseous feed.The partial pressure of the cyclic acetals is related to the vaporpressure of the pure compounds at reaction temperature. Partial pressure(PP) of a given component “b” is defined: P(absolute)×(mole fraction ofb in the mixture). Mole fraction is the portion of moles of thecomponent in the total moles of a mixture. The partial vapor pressuresof organic materials in this invention at reaction pressure andtemperature must remain below the vapor pressure of the pure materialsat that reaction temperature to avoid condensation. In essence, loweringreactor absolute pressure of a given mole fraction of reactant cyclicacetal in the feed will thereby lower the partial pressure of thereactant cyclic acetal. The vapor pressures of pure materials may beobtained by normal calculations with established physical constants orobtained from vapor pressure tables. For example one such method ofvapor pressure calculation for the pure compound2-n-propyl-1,3-dioxolane (PDX) would be: vapor pressure of PDX in mmHg=10**((−0.2185×(A/K)+B) where A=10183.9; K=Temperature of the PDX indegrees Kelvin; and B=+8.363358. Thus the vapor pressure of pure PDXwould be about 4560 mm Hg (607.95 kPa) at 200 degrees Celsius (473degrees K).

Without being bound to a theory, not having liquid condensation on thesurface of the supported noble metal catalyst facilitates the transferof gaseous hydrogen into the catalytic cycle. In addition, the lack ofliquid organic materials on the surface of the catalyst reduces theability for product reaction leading to unwanted byproducts. Indeed, wehave also found that decreased residence time on the catalyst increasesthe selectivity to the desired hydroxyether hydrocarbon product withoutsignificantly affecting the reaction rate of the catalytic process. Itis most desirable to hold the residence time of materials on thecatalyst surface at between 0.25 and 1.5 seconds.

The hydrogenolysis reaction uses hydrogen as both a gaseous feed mediumand reactant in this invention. A hydrogenolysis reaction uses hydrogento cleave the carbon-oxygen bond of either the 1,2 carbon-oxygen bond orthe 2,3-carbon-oxygen bond by means of the supported noble metalcatalyst. The purity of the hydrogen being fed to the reactor is highenough to effect the desired reaction and not contain significantamounts of impurities that could act as poisons or inhibitors. Inerthydrocarbons such as methane, ethane, propane and butane are managed bynormal gas purging methods to keep the desired partial pressure ofreactant hydrogen present in the reactor. For certain impurities such ascarbon monoxide, methods such as nickel methanation catalyst beds andthe like can be used to convert CO into an inert methane impurity andthereby control the concentration of CO in the reactor feed stream.

The amount of hydrogen fed in the continuous process can be that amountsufficient to enhance selectivity to the hydroxy ether mono-hydrocarbon.The amount of hydrogen used will vary depending on the reactionconditions and type of cyclic compound used as the substrate, butgenerally, a molar ratio of hydrogen to cyclic compound of at least 5:1is suitable. Other examples of molar ratios of hydrogen to cycliccompounds include at least 10:1, or at least 50:1, or at least 100:1, orat least 150:1, or at least 170:1, or at least 190:1, or at least 200:1,or at least 250:1, and can be as high as desired. It is desirable toadjust the molar ratio to increase selectivity. The selectivity isimproved with the catalyst compositions of the invention when the molarratio exceeds 100:1, or is at least 125:1, or is at least 150:1.

The reactor pressures used may be from one atmosphere (14.7 psig) up to5000 psig Higher reactor pressures have the advantage of reducing theformation of ester byproducts such as ethyl butyrate, ethylene glycolmonobutyrate, and 2-n-butoxybutanol monobutyrate in the case where2-propyl-1,3-dioxolane is used as the feed material. Particularly usefulpressure ranges are within 200 to 1000 psig for practical operation ofthis invention.

The reactor design is not crucial for the operation of this invention.The reactor should be designed to permit a gaseous mixture of hydrogenand the cyclic compounds to pass over the supported noble metal catalystand exit the reactor zone with the desired hydroxy ether hydrocarbon asa gaseous product mixture. Convenient designs include plug flow reactorssuch as long tubular designs and multi-tube short path designs. Otherreactors known as “pancake” reactors have a wide continuous catalyst bedthat is of a relatively short path. The process can also be conducted inexotic designs such as spinning basket or Berty type reactors can beused. In all reactor designs, however, the catalyst bed should remain ata temperature above the dew point of the reactants and products at thereactor conditions used. Additionally, the design of the reactor feedsystem should be designed to keep the feed composition compositionallybalanced to that the partial pressures of the cyclic compounds fed tothe reactor remain above the dew points of the cyclic compounds underthe operating reactor conditions. This may be easily achieved by use ofvapor liquid equilibrium feed chambers or by controlling the rates ofliquid and hydrogen feed rate to the reactor via a mixing chamber toassure complete vaporization of the cyclic compounds at the reactorconditions prior to contact with the hydrogenolysis catalyst bed and tomaintain the cyclic compounds at the proper feed partial pressure.

No polyhydroxyl hydrocarbon co-solvent feed, such as ethylene glycol, isrequired in a vapor phase hydrogenolysis conversion process. Thus, anadvantage of the current process is conducting a conversion of cycliccompounds to their corresponding hydroxy ether hydrocarbon reactionproducts in the absence of a liquid solvent feed, such as ethyleneglycol, at high selectivities.

The product stream is withdrawn from the reaction zone. The productstream contains a hydroxy ether reaction product of the cycliccompound(s) with hydrogen. The reaction zone reaction conditions can beset to ensure that the hydroxy ether reaction product remains above itsdew point. The reaction conditions can also be set within the reactionzone to ensure that the product stream withdrawn from the reaction zoneremains above its dew point and is a vapor. When the product stream iswithdrawn from the reaction zone as a vapor, the product stream willalso contain other types of compounds in minor amounts, such asby-products, hydrogen gas, and un-reacted cyclic acetal or ketalcompounds.

In the vapor phase hydrogenolysis of the cyclic compounds over aheterogeneous supported noble metal catalyst, the noble metal catalystis not withdrawn in the product stream. The product stream withdrawnadvantageously does not contain any appreciable quantities of the noblemetal catalyst that have to be separated from the desired hydroxy etherhydrocarbon. In one embodiment of the invention in the product streamwithdrawn from the reaction zone contains less than 500 ppmw of themetal catalyst used in the reaction zone, or less than 100 ppmw, or lessthan 50 ppmw, or less than 25 ppmw, or less than 10 ppmw, or less than 5ppmw, or less than 2 ppmw, based on the weight of all ingredients fed tothe reaction zone.

Suitable hydroxy ether hydrocarbons are the reaction products of thecyclic compounds with hydrogen gas resulting in a hydrocarbon with atleast one ether linkage and at least one primary hydroxyl group. Thehydroxy ether hydrocarbons may contain secondary hydroxyl groups, andadditional ether linkages. In one embodiment, the hydroxy etherhydrocarbons are represented by the general formula:

R⁶OR⁷OH

wherein R⁶ is a branched or un-branched C₁-C₅₀ alkyl, C₂-C₅₀ alkenyl,aryl-C₁-C₅₀ alkyl, aryl-C₂-C₅₀ alkenyl-, C₃-C₁₂ cylcoalkyl, or a C₃-C₅₀carboxylate ester; and wherein the alkyl, alkenyl, aryl, and cycloalkylgroups of R⁶ optionally contain 1, 2, or 3 oxygen atoms in the alkyl,cycloalkyl, or alkenyl group and are optionally substituted with 1, 2,or 3 groups independently selected from —OH, halogen, dialkylamino,aldehyde, ketone, carboxylic acid, ester, ether, alkynyl, dialkylamide,anhydride, carbonate, epoxide, lactone, lactam, phosphine, silyl,thioether, thiol, and phenol.

In the case that the cyclic compound starting material is a cyclicketal, then R⁶ branched at least at the carbon adjacent the etherlinkage in the general formula above. The branch can be selected fromthe same groups as R⁶.

R⁷ is a branched or un-branched divalent C₁-C₅₀ alkyl, C₂-C₅₀ alkenyl,aryl-C₁-C₅₀ alkyl, aryl-C₂-C₅₀ alkenyl-, C₃-C₁₂ cylcoalkyl, or a C₃-C₅₀carboxylate ester; and wherein the divalent alkyl, alkenyl, aryl, andcycloalkyl groups of R⁷ optionally contain 1, 2, or 3 oxygen atoms inthe divalent alkyl, cycloalkyl, or alkenyl group and are optionallysubstituted with 1, 2, or 3 groups independently selected from —OH,halogen, dialkylamino, aldehyde, ketone, carboxylic acid, ester, ether,alkynyl, dialkylamide, anhydride, carbonate, epoxide, lactone, lactam,phosphine, silyl, thioether, thiol, and phenol.

The R⁶ group of the general formula may be a branched or un-branchedC₁-C₁₂ alkyl or aryl-C₁-C₁₂ alkyl; optionally substituted with 1, 2, or3 groups independently selected from —OH, halogen, dialkylamino,aldehyde, ketone, carboxylic acid, ester, ether, alkynyl, dialkylamide,anhydride, carbonate, epoxide, lactone, lactam, phosphine, silyl,thioether, thiol, and phenol.

The R⁷ group of the general formula may be a divalent branched orun-branched C₁-C₁₂ alkyl or a C₂-C₁₂ alkenyl; and wherein the divalentalkyl or alkenyl groups of R⁷ optionally contain 1, 2, or 3 oxygen atomsin the divalent alkyl or alkenyl groups and are optionally substitutedwith 1, 2, or 3 groups independently selected from —OH or halogen.

In each case above, the alkyl groups may have from 1-8 carbon atoms, or1-6 carbon atoms, or 1-4 carbon atoms, and the alkenyl groups may havefrom 2-8 carbon atoms, or 2-6 carbon atoms, or 2-4 carbon atoms.

Examples of the types of hydroxy ether hydrocarbons that are made by theprocess of the invention include ethylene glycol propyl ether, ethyleneglycol butyl ether, ethylene glycol 2-ethylhexyl ether, diethyleneglycol methyl ether, diethylene glycol ethyl ether, diethylene glycolpropyl ether, diethylene glycol butyl ether, propylene glycol methylether, ether, 3-butoxy-1,2-propanediol, 2-butoxy-1,3-propanediol,2-isopropoxyethanol, isopropoxy-2-propanol, 3-isopropoxypropanol,2-(3-methyl-2-butoxy)ethanol, 3-(3-methylbutan-2-yloxy)propanol,2-(4-methylpentan-2-yloxy)ethanol, 3-(4-methylpentan-2-yloxy)propanol,3-(4-methylpentan-2-yloxy)-1,2-propanediol,2-(4-methylpentan-2-yloxy)-1,3-propanediol, 2-(pentan-2-yloxy)ethanol,3-(pentan-2-yloxy)-propanol, 2-(pentan-2-yloxy)-1,3-propanediol,3-(pentan-2-yloxy)-1,2-propanediol, 2-(methyl-hexyloxy)ethanol,3-(methyl-hexyloxy)-propanol, 2-(methyl-hexyloxy)-1,3-propanediol,3-(methyl-hexyloxy)-1,2-propanediol.

The hydroxy ether hydrocarbons have a wide variety of uses. They can beused as solvents, coalescents and plasticizers in all-purpose cleaners,architectural coatings, automotive coatings, cleaners for ink processes,coalescents for latex paints, coatings for plastics, floor cleaners,solvents for removing photoresists in semiconductor wafers, glasscleaners, household cleaners, industrial cleaners, industrial coatings,and metal brighteners and cleaners. They can be used a solvents for alarge variety of coatings resin types, including alkyd, phenolic,maleic, epoxy, and nitrocellulose resins. They are also useful asretarder solvent for lacquers, improving gloss and flow-out. Some of thehydroxy ether hydrocarbons can also be used in amine-solubilized,water-dilutable coatings because of their high flash point, completewater solubility, slow evaporation rate, low surface tension, and highcoupling efficiency. As coalescents, they improve film integrity in botharchitectural and industrial maintenance latex paints.

The desired hydroxy ether hydrocarbon can be readily separated from theproduct stream. One particularly useful method is to cool the gaseousreactor product stream to below the dew point of the reaction productsand unreacted cyclic compounds to form a liquid product and from which agaseous stream comprised primarily of hydrogen gas (greater than 70 vol.%) is easily separated. When the cooling is carried out at reactorpressure, very little energy is required to re-circulate the un-reactedhydrogen back as a feedstock reactant stream to the reactor vessel. Thecondensed liquid products may then be recovered and purified by knownmethods, such as distillation, extraction, crystallization and the liketo obtain the desired product. Similarly, a liquid scrubber may beemployed to recover condensable liquid products from the gaseous reactoreffluent. These and other known methods of product recovery may be usedin combination with the hydrogenolysis process of this invention.

The process of the invention is carried out batchwise or continuously,preferably continuously.

WORKING EXAMPLES

The liquid feed part of the unit consists of a 100 mm graduated burettefeed tank for the acetal feed. This is connected to a flow programmablehigh pressure lab scale ball and check feed pump (Eldex ReciPro OptosSeries Model 1). All equipment under pressure is constructed of 316stainless steel tubing or fittings. The discharge of the pump leads to ⅛inch diameter tubing that is connected to a fitting on the top of apreheater section. The preheater is constructed of ¼ inch outer diametertubing. The tubing is packed with fused alumina. A thermocouple extendsinto the alumina bed to allow for monitoring of the internaltemperature. The preheater is wrapped with electrical heating tapecontrolled by an adjustable thermostat. The internal temperature of thepreheater is maintained +/−5° C. of the desired reaction temperature.The exit of the preheater is connected to a fitting on the top of thereactor. This fitting is further connected to a ⅛ inch diameter tubingsection that leads to a vaporization section prior to the catalyst bed.Hydrogen feed is supplied from high pressure cylinders of zero gradehydrogen via a high pressure regulator to a lab scale Brooks mass flowcontroller. Nitrogen feed, used for purging and other inert gas needs,is fed by a similar design from a high pressure cylinder via a gasregulator through another dedicated Brooks mass flow controller forinert gas flow. The discharges from these two mass flow controllers areconnected by a manifold to a ¼ inch diameter tubing feed line that isconnected to the top of the reactor. The hydrogen or inert gas feedsenter the reactor by an annulus around the ⅛ inch diameter liquid feedline and mix with the liquid above the vaporization section in thereactor.

The reactor is a 24″ long×½″ diameter section of high pressure tubingheld in a vertical arrangement. The top part of the reactor consists ofa stainless steel Swagelok cross with the appropriate fittings requiredto permit liquid feed to the reactor via the ⅛ inch diameter tubing, topermit hydrogen or other gas feed to the reactor via ¼ inch tubing andto connect to a pressure gage and a safety pressure relief device. Thetop portion of the reactor consists of a bed 4″ deep of fused aluminabeads 2-3 mm in diameter that are used for the vaporization of theliquid feed in contact with the gaseous hydrogen feed. A thermocouple isattached to the outside skin of the reactor about 1″ from the bottom ofthe vaporization bed and is externally wrapped with heat resistantinsulation tape to measure the skin temperature of the metal surface asbeing heated from the inside by the heated gases. A spacer of pyrex woolpacking is used to separate the vaporizer section from the catalystsection of the bed that is downstream from the vaporizer. The lab unitnormally uses 10 cubic centimeters of the hydrogenation catalyst used inthis invention. The depth of the bed is approximately 5 inches deep. Thebed is held in place by another spacer of pyrex wool packing and asupport of ¼ inch diameter tubing to hold it in place. A secondthermocouple is attached with similar insulation to the outer skin ofthe reactor tubing about 2 thirds of the depth of the catalyst bedtowards the bottom. A third K-type thermocouple extends from the exit ofthe reactor into the reactor to a depth of approximately ½ inch of thebottom of the catalyst bed. The reactor tubing is placed inside a “clamshell” heater that is electrically heated and controlled by thetemperature recorded by the thermocouple extending into the catalystbed.

The ½ tubing of the bottom of the reactor is connected by appropriateSwagelok fittings to a 1″ 316 stainless steel “T”. This “T” is filledwith ⅛″ stainless steel Penn State packing material as a coalescer andis cooled by way of a circulating bath to copper tubing on the outsideof the “T”. This “T” is a high pressure vapor/liquid (V/L) separatorwhere liquid product is condensed for recovery. The bottom of the “T”has a needle valve connected to a small section of ⅛″ diameter tubingwhere the collected liquid product is drained periodically and analyzedby gas chromotograph. The side fitting of the “T” consists of ½ tubingthat provides an exit for the uncondensed hydrogen and other gases. Theside fitting also has a thermocouple in it to measure the insidetemperature of the “T”. The gases leaving the side tubing of the “T” arethen directed upwards to a back pressure regulator that controls thepressure of the reactor. Gases leaving downstream from the back pressureregulator are at ambient pressure and proceed to an on-line gaschromatograph that allows for analysis of non-condensed products.

Example 1 Hydrogenolysis Of 2-propyl-1,3-dioxolane Over 1% Pd/1000 ppmNion Alumina

The liquid feed tank of the unit was filled with a cyclic acetal of thisinvention, 2-n-propyl-1,3-dioxolane (PDX). The reactor had been chargedwith 10 cc (8.5 grams) of a catalyst containing 1% Pd/1000 ppmw Ni onalumina sphere supplied by BASF (SEO86630). The hydrogen flow was set at7950 sccm and the back pressure regulator was set to 500 psig. Thecatalyst bed temperature target was set at 210 degrees Celsius. Afterreaching 210 degrees, the reactor was permitted to equilibrate at 210degrees Celsius for fifteen minutes. After that period, the PDX pump wasstarted with a target feed rate of 0.28 ml/minute. Liquid productsamples were collected hourly as was operating data. The samples wereweighed and analyzed by gas chromatographic analysis on AgilentTechnologies 7890A series machine having a thermal conductivitydetector. The column used was a 30 m J & W 122-3232 DB-FFAP capillarycolumn. A 2 minute hold was used at 50 degrees C. followed by a 10deg/min heat up rate to a final temperature of 250 deg C. and a final 10minute hold at 250 deg. C. Response factors were used in normal standardpractice to obtain the weights of the different components.

The last five hours of samples and feed level drop were used to performcalculations on the conversion of PDX into the desired product2-n-butoxyethanol. A total of 79.9 g of PDX was fed during this period.A total of 24.3 grams of PDX was recovered, 51.4 grams of2-n-butoxyethanol, 0.18 grams of ethyl butyrate, 0.07 g of normalbutanol, 2.38 g of 1,2-n-butoxyethane, 0.29 grams ofmethyl-n-butylether, 0.35 g of 2-n-butoxyethanol monobutyrate ester,0.85 grams of ethylene glycol and 0.08 grams of other organic materialswere recovered. The conversion of the PDX was 79% with a selectivity ofconsumed PDX to 2-n-butoxyethanol of 92.6%. The H2/PDX feed mole ratioof this run was 160:1 with the PDX partial pressure in the reactor at165 mm Hg and a catalyst residence time of 1.5 seconds. The specificproduction rate of the desired 2-n-butoxyethanol was 64 lb/ft³·h.

Example 2 Varying Process Conditions

The Table 1 of runs below used the same charge of catalyst, namely a 10cc sample of BASF Catalysts 1% Pd/0.1% Ni alumina sphere catalyst(SEO86630) in the above described unit and demonstrates the effect ofvarious reaction parameters on per pass conversion and selectivity.

TABLE 1 Temp H2/ PDX, gas, Conver- EB glyme Ester MBE BuOH Run (° C.)PDX Psig cc/min sccm sion Selectivity Selectivity SelectivitySelectivity Selectivity 2 195 170 300 0.10 3200 85.3% 90.5% 7.0% 1.5%0.38%  0.59% 3 230 80 500 0.58 8535 73.3% 93.4% 4.5% 0.64%  1.2% 0.12% 4230 150 500 0.40 10600 77.3% 88.5% 7.5% 1.8% 1.7% 0.32% PDX =2-n-propyl-1,3-dioxolane; EB = 2-n-butoxyethanol; MBE =methyl-n-butylether; ester = ethyl n-butyrate and EB monobutyrate; glyme= 1,2-di-n-butoxyethane.

Comparative Example 1 Use of an Un-Promoted 1% Pd/Alumina Catalyst

Unpromoted catalysts having a Pd loading of 1% or greater tend to bevery active, but not as selective as the nickel promoted catalysts asindicated in these comparative examples.

The reaction was carried out as described above with a 10 cc charge of1% Pd on ⅛″ alumina spheres (BASF Catalysts 1% Pd AS-38). The last fivehours of samples and feed level drop were used to perform calculationson the conversion of PDX into the desired product 2-n-butoxyethanol. Atotal of 77.2 g of PDX was fed during this period. A total of 3.4 gramsof PDX was recovered, 59.3 grams of 2-n-butoxyethanol, 0.02 grams ofethyl butyrate, 0.19 g of normal butanol, 9.5 g of 1,2-n-butoxyethane,0.21 grams of methyl-n-butyl ether, 0.30 g of 2-n-butoxyethanolmonobutyrate ester, 3.36 grams of ethylene glycol and 0.20 grams ofother organic materials were recovered. The conversion of the PDX was99% with a selectivity of consumed PDX to 2-n-butoxyethanol of 80.9% anda selectivity of consumed PDX to 1,2-dibutoxyethane of 17.6%. Thespecific production rate of the desired 2-n-butoxyethanol was 74lb/ft³·h.

Comparative Example 2 Varying Process Conditions

The table below shows the reduced selectivity of the catalyst ofComparative Example 1 at other reaction conditions along with the highproduction of undesired byproducts such as 1,2-dibutoxyethane and itsco-produced ethylene glycol.

TABLE 2 Temp H2/ PDX, gas, Conver- EB glyme Ester MBE BuOH Run (° C.)PDX psig cc/min sccm sion Selectivity Selectivity SelectivitySelectivity Selectivity 6 195 170 300 0.10 3200  100% 82.4% 15.6% 0.97%0.44% 0.32% 7 195 170 300 0.20 6400 91.5% 63.8% 34.5%  1.3% 0.20% 0.04%8 210 150 500 0.42 11670 94.3% 75.2% 24.4% 0.19% 0.15% 0.06%

Comparative Example 3 Use of Un-Promoted Catalysts with Less than 1% Pd

The reaction was carried out as described above with a 10 cc charge of0.5% Pd on 1/16″ alumina spheres from Evonik Degussa (Evonik E2123) Thelast five hours of samples and feed level drop were used to performcalculations on the conversion of PDX into the desired product2-n-butoxyethanol. A total of 77.9 g of PDX was fed during this period.A total of 42.4 grams of PDX was recovered. 31.5 grams of2-n-butoxyethanol, 0.02 grams of ethyl butyrate, 1.25 g of1,2-n-butoxyethane, 0.01 grams of methyl-n-butyl ether, 0.20 g of2-n-butoxyethanol monobutyrate ester, 0.47 grams of ethylene glycol and0.13 grams of other organic materials were recovered. The conversion ofthe PDX was 58.3% with a selectivity of consumed PDX to2-n-butoxyethanol of 94.5% and a selectivity of consumed PDX to1,2-dibutoxyethane of 5.07%. The specific production rate of the desired2-n-butoxyethanol was 39 lb/ft³·h. These catalysts have very highselectivity to the desired glycol ether, but a lower rate of productionthan the 1% catalysts.

Comparative Example 4 Use of 1% Pd Catalyst Promoted with Ni and Na

The reaction was carried out as described above with a 10 cc charge of1% Pd/0.1% Ni/###% Na on ⅛″ alumina spheres (BASF Catalysts SEO #9582).A total of 79.3 g of PDX was fed during this period. A total of 55.3 gof PDX was recovered. 20.8 g of 2-ethoxybutanol, 0.25 grams of ethylbutyrate, 0.89 g of 1,2-n-butoxyethane, 0.40 grams of methyl-n-butylether, 0.19 g of 2-n-butoxyethanol monobutyrate ester, 0.23 grams ofethylene glycol and 0.09 grams of other organic materials wererecovered. The conversion of the PDX was 39.9% with a selectivity ofconsumed PDX to 2-n-butoxyethanol of 90.4%. The specific production rateof the desired 2-n-butoxyethanol was 26 lb/ft³·h. The per passconversion of this catalyst is too low to be industrially relevant.

What we claim is:
 1. A process comprising contacting cyclic compoundswith hydrogen in the presence of a metal catalyst in a reaction zone toproduce a vapor hydroxy ether hydrocarbon, withdrawing from the reactionzone a vapor product stream comprising a vapor hydroxy ether hydrocarbonand hydrogen, followed by separating and recovering a hydroxy etherhydrocarbon composition from the product stream, wherein said cycliccompounds comprise a cyclic acetal, cyclic ketal, or a combinationthereof.
 2. The process of claim 1, wherein the conversion of cycliccompounds is at least 70% and the selectivity to the production ofhydroxy ether monohydrocarbons is at least 85%.
 3. The process of claim2, wherein the selectivity is at least 90%.
 4. The process of claim 3,wherein the conversion is at least 75%.
 5. The process of claim 4,wherein the cyclic compound comprises a cyclic acetal.
 6. The process ofclaim 1, wherein a diether co-product is generated in an amount of lessthan 5 wt %.
 7. The process of claim 1, wherein the reaction zoneconditions are above the dew point of product stream.
 8. The process ofclaim 1, wherein the reaction in the reaction zone is conducted in theabsence of a liquid compound.
 9. The process of claim 1, wherein thecyclic compound comprises comprises 2-propyl-1,3-dioxolane.
 10. Theprocess of claim 1, wherein the temperature of the reaction zone is atleast 180° C.
 11. The process of claim 10, wherein the partial pressurewithin the reaction zone is above the dew point of all the cycliccompounds within the composition fed to the reaction zone at reactionzone temperature.
 12. The process of claim 1, wherein the selectivity tothe hydroxy ether compounds is at least 90 mole %.
 13. The process ofclaim 1, wherein the cyclic compounds have a practical vapor pressure inexcess of 10 mm Hg at the temperature within the reaction zone.
 14. Theprocess of claim 13, wherein the practical vapor pressure of the cycliccompounds are at least 50 mm Hg at the temperature within the reactionzone.
 15. The process of claim 13, wherein the temperature within thereaction zone is within a range of 180° C. to 250° C.